1746-OW8/A Relay Output Module: Specs Decoded

Introduction: Why Spec Clarity Matters

How often do engineers misapply a relay output module because a datasheet parameter was overlooked? The Allen-Bradley 1746-OW8/A, a discontinued SLC 500 relay output module, remains widely deployed in legacy systems. Understanding its exact specifications is critical for safe replacement and integration. This article decodes the key parameters—input voltage, output current, communication protocol, and mounting type—to support informed decisions.

Product Overview: 1746-OW8/A at a Glance

The 1746-OW8/A is an eight-channel electromechanical relay output module for the SLC 500 platform. It provides isolated normally-open contacts, switching both AC and DC loads. Each output is rated for 1.5 A at 120 VAC or 1.2 A at 24 VDC, with a continuous 8 A per common and 16 A per module. The module operates on 5-265 VAC or 5-125 VDC, making it versatile for mixed-voltage control environments.

Decoding Critical Specifications

Input Voltage and Output Current

The module’s field-side operating voltage range is 5-265 VAC or 5-125 VDC. Output current capacity is 1.5 A per point at 120 VAC and 1.2 A per point at 24 VDC. Continuous current per common is 8 A, and 16 A per module. These ratings ensure reliable switching of motor starters, solenoids, and pilot devices.

Communication Protocol and Backplane Power

The 1746-OW8/A communicates via the SLC 500 backplane, drawing 85 mA at 5V DC and 90 mA at 24V DC. The chassis backplane supplies 5.1V DC @ 10A and 24V DC @ 2.88A to all modules. No external communication protocol is used; data transfer occurs through the backplane to the processor.

Mounting Type and Isolation

Mounting is chassis-based, compatible with 1746-A4, -A7, -A10, and -A13 chassis (4, 7, 10, or 13 slots). All chassis are panel-mount. Relay isolation is 1500 VAC between contacts and backplane, ensuring signal integrity. The module is not hot-swappable; power must be removed before installation or wiring.

Application Scenarios and Compatibility

Typical applications include factory automation, packaging equipment, material handling, and process control panels. The module’s isolated contacts allow direct control of AC and DC loads. It is compatible with SLC 500 processors and remote I/O racks. For migration, Rockwell recommends Compact 5000 I/O with the Logix platform, but the 1746-OW8/A remains a viable option for existing installations.

Supply and Support

As a discontinued module, sourcing genuine 1746-OW8/A units requires a trusted partner. PLCXpert specializes in verified OEM and equivalent parts, offering expert technical consultation to ensure correct selection. With competitive pricing and flexible shipping, we support your legacy automation needs. Contact PLCXpert today for technical assistance, competitive pricing, and reliable supply of your industrial automation parts.

FAQ

What is the output current rating of the 1746-OW8/A?

1.5 A per output at 120 VAC and 1.2 A per output at 24 VDC, with 8 A continuous per common and 16 A per module.

Can the 1746-OW8/A be hot-swapped?

No, the module is not hot-swappable. Power must be removed before installation, removal, or wiring.

What mounting chassis are compatible with the 1746-OW8/A?

It mounts in 1746-A4, -A7, -A10, or -A13 chassis, which are panel-mount.

What is the operating voltage range?

5-265 VAC or 5-125 VDC for field-side loads.

Conclusion

Accurate parameter interpretation prevents misapplication and downtime. The 1746-OW8/A offers robust relay output capabilities for legacy SLC 500 systems. For verified specifications and expert support, trust PLCXpert—your trusted industrial automation partner.